It is known to provide material handling systems that include vacuum cups or the like that are adapted to be engaged with an object, such as a substantially flat object or panel or the like, and to lift and move the object to a desired location. Such vacuum cups or suction cups may be moved into engagement with the object, and a vacuum source may be actuated to create a vacuum between the object and the cup such that the object is retained to the cup as it is transported to the targeted area. An example of such a vacuum cup is disclosed in U.S. Pat. No. 4,662,668, which is hereby incorporated herein by reference.
As shown in FIGS. 1-4, a typical bellows-type vacuum cup 10 may include a body portion or back panel portion 12 and a bellows-type or pleated skirt or seal 14 extending from body portion 12. The body portion may include a vacuum port or opening or aperture 16 therethrough for receiving or connecting to a vacuum source to draw air out of a cavity 18 defined between the vacuum cup and an object 20. The bellows-type pleated skirt 14 may comprise a flexible, resilient, elastomeric material or the like, and may flex to engage the object 20 and to provide a substantially airtight seal between the vacuum cup 10 and the object 20. The vacuum cup 10 may further include a bushing or fitting or the like 22, such as a threaded brass fitting or bushing, for connection to the vacuum source. Optionally, the bushing or fitting may be adapted or configured to connect to a proximity sensor (not shown), such as to a threaded end of a proximity sensor of the type described in U.S. Pat. No. 4,662,668. The sensor may detect the presence of an object, such as the object 20 in FIG. 4, that is at or proximate to the sensor. In such an application with an object sensor at the central port or opening of the vacuum cup, the vacuum cup may include a separate vacuum port (such as shown in phantom at 17 in FIGS. 1 and 3) for connection to the vacuum source.
The vacuum source is operable to draw air through the vacuum port and out of the cavity to create a partial vacuum between the vacuum cup and the object. Often, the vacuum source remains operational to maintain the partial vacuum between the object and the vacuum cup to retain the object on the vacuum cup throughout transportation of the object from one location to the other. When the vacuum cup and object arrive at the targeted location, the vacuum cup may be pulled away from the object, while the object is substantially retained in a particular location, such that the object is stripped from the vacuum cup, all while the vacuum source remains operational to create/maintain the vacuum.
For example, vacuum cups often may engage and substantially seal against objects, and may carry the objects to a magnetic belt or conveyor that is positioned above the objects. In such applications, the vacuum cups may lift or raise the object up to the overhead or raised magnetic conveyor and may release the article at the overhead conveyor. Typically, the vacuum cups are pulled upwardly until the panel or object engages the magnetic conveyor. The vacuum cups are then pulled further upwardly (while the panel or object is retained at the magnetic conveyor) to strip or dislodge the cups from the panel or object, whereby the object is retained on the magnetic conveyor via the magnetic attraction between the metallic object and the magnetic conveyor.
The entire process of engaging the object, lifting the object upward to the magnetic conveyor and stripping the cups off of the object at the conveyor is typically performed with the vacuum source activated, such that the vacuum source creates the partial vacuum at the vacuum cup and does not release the vacuum to assist in releasing the cup from the object or panel. The vacuum source may remain operational throughout this process to avoid having to activate and deactivate the vacuum source multiple times while moving multiple objects from one location to the next. However, the pulling of the vacuum cup or cups from the object while the vacuum is applied between the vacuum cup and the object may cause excessive wear to the vacuum cups and, thus, may lead to premature failure of the vacuum cups over time.